Intake vortex whistle silencing apparatus and methods

Abstract

A diametrically opposed pair of radially inwardly directed vortex-disturbing tabs are secured to a compressor intake assembly to eliminate vortex whistle therein.

What is claimed is: 
     
       1. Apparatus operable to supply compressed gas to a pneumatically-operated device, comprising: (a) a rotationally drivable centrifugal compressor having an axis of rotation, and an annularly shaped inlet circumscribing said axis;   (b) gas intake means associated with said compressor for flowing gas into said inlet in a swirling pattern generally centered about said axis and having an origin spaced axially outwardly from said inlet, said intake means having a circular, generally radially outwardly facing inlet opening encircling said axis, and an annular gas flow passage connecting said compressor inlet and said inlet opening of said gas intake means; and   (c) means for disturbing only a relatively small portion of said swirling pattern to attenuate whistle noise caused thereby.   
     
     
       2. A gas turbine engine auxiliary power unit comprising; (a) rotatable turbine means;   (b) power compressor means rotationally coupled to said turbine means;   (c) combustor means for receiving compressed air discharged from said power compressor means, mixing the received air with fuel, burning the fuel-air mixture to form a hot, expanded gas, and forcing the expanded gas through said turbine means to rotate the same;   (d) load compressor means drivably coupled to said turbine means for supplying compressed air to pneumatically-operated apparatus;   (e) air intake means for directing ambient inlet air into said load compressor in a vortex flow pattern; and   (f) means associated with said air intake means for causing a relatively minor disturbance in said vortex flow pattern to attenuate vortex whistle caused thereby,   said load compressor means comprising a centrifugal compressor having a rotational axis and an annular inlet opening, and said air intake means having a generally radially facing inlet opening, a generally axially facing discharge opening positioned adjacent said compressor inlet opening, and an annular air flow passage circumscribing said axis and opening outwardly through said inlet and discharge openings of said air intake means, said vortex flow pattern extending between said inlet and discharge openings of said air flow passage.   
     
     
       3. The auxiliary power unit of claim 2 wherein said air intake means include a series of inlet guide vane means positioned in a mutually spaced array around said inlet opening of said air intake means. 
     
     
       4. The auxiliary power unit of claim 2 wherein said disturbance causing means include at least one vortex-disturbing member projecting generally radially into said flow passage adjacent said inlet opening of said air intake means. 
     
     
       5. The auxiliary power unit of claim 4 wherein said disturbance causing means comprise a pair of vortex-disturbing members projecting generally radially into said flow passage adjacent said inlet opening of said air intake means. 
     
     
       6. The auxiliary power unit of claim 5 wherein said pair of vortex-disturbing members are positioned in a generally diametrically opposed relationship. 
     
     
       7. The auxiliary power unit of claim 6 wherein each of said vortex-disturbing members is connected to a different one of a generally diametrically opposite pair of said inlet guide vane means. 
     
     
       8. A method of operating a centrifugal compresor having an axis and an axially facing annular inlet opening centered about the axis, said method comprising the steps of: (a) connecting to the compressor an intake body having first and second concentric, mutually spaced wall sections forming therebetween a gas flow passage communicating with the compressor inlet opening and defining an annular, radially outwardly flared extension thereof, said wall sections having outer end portions defining a circular, radially outwardly facing inlet opening portion of said flow passage;   (b) securing between said wall section outer end portions a series of adjustable inlet guide vanes which extend in a mutually spaced array around the circumference of said flow passage inlet opening portion;   (c) driving the compressor to draw gas into said inlet opening portion of said flow passage, inwardly through said flow passage, and into the compressor inlet opening;   (d) adjusting said inlet guide vanes to cause the gas to assume a vortex flow pattern as it traverses said flow passage; and   (e) positioning in said flow passage adjacent its inlet opening a vortex-disturbing member to intercept an axial and radial portion of said vortex flow pattern to create therein a random zone of turbulence extending partially around the circumference thereof.   
     
     
       9. The method of claim 8 further comprising the step of positioning in said flow passage adjacent its inlet opening a second vortex-disturbing member to intercept a second axial and radial portion of said vortex flow pattern to create therein a second zone of turbulence extending partially around the circumference thereof and positioned generally diametrically opposite said first-mentioned zone of turbulence. 
     
     
       10. The method of claim 8 wherein said positioning step includes the step of connecting each of said vortex-disturbing members to one of said inlet guide vanes. 
     
     
       11. The method of claim 9 wherein said positioning step includes the step of connecting each of said vortex-disturbing members to one of said inlet guide vanes.